Electrical device



May 27, l1930. 1 T. ROBINSON ELECTRICAL DEVICE original Filed March 10,1927' Inventor: /7 Y u LewsTTObisOh,

HIS Attorney Patented May 27, 1930 LEWIS T. ROBINSON, OF NISKAYUNA, NEWYORK, ASSIGNOR T0 GENERAL ELECTRIC COMPANY, A. CORPORATION OE NEW YORKELECTRICAL DEVIOE Application led March 10, 1927, Serial No. 174,355.Renewed February 10, 1928.

My invention relates to speech current devices producing phonographrecords such as those used reproducing sounds from suchl records or forconvertingsound impulses into electrical impules or vice versa.. Anobject of my invention is the provision of an improved device of thischaracter, the moving element of which follows accurately the complexwave form peculiar to sound.

In the construction of speech current apparatus utilized to convertsound impulses into electrical impulses or to convert electricalimpulses into sound, difficulties have been encountered in providing thedevice with a moving ,system which would not produce objectionabledistortions of these impulses. These distortions have been found to bedue largely to inertia ell'ects of the moving parts and to excessivevibration thereof at frequencies corresponding to their naturalvibration periods. While these effects, particularly the former, havebeen greatly lessened by a reduction inthe mass of the moving parts tothe minimum value found practicable, distortion is most effectivelyprevented by the proper damping of the moving system. v l

In accordance with my invention these difficulties are avoided by theprovision of a damping means for the moving system depending in itsaction upon fluid friction and adjustable in its effects withincomparatively wide limits.

My invention will be better understood from the following descriptiontaken in connection with the accompanying drawing, and its scope will bepointed out in the appended claims.

Referring-to the drawing, Fig.' 1 is a side elevation partly in sectionof a device illustrating one embodiment of my invention; Fig. 2 is across sectional view of the same at right angles to that of Fig. 1; andFig. 3 is a detail view of an alternative construction. Inasmuc-h as thedevice herein disclosed is -very small, it has been illustrated on agreatly enlarged scale. rllhe device is shown comprising a built-upframe 1, having a projecting handle portion 2 by which it is supportedand having right and left castings 3. The frame l has end plates 4, atop plate 5 and a bottom plate 6 forming therewith a hollow member orcasing containing the moving system and the damping liquid 7, preferablyoil. Permanent magnet 8 spans the casin and has its poles engaging polepieces 9 w ich are set into the castings 3. rIhe pole pieces tendingpolar projections between which lie the coils 10 forming the winding.The 1aminated soft iron armature 12 is supported in a vertical positionbetween the polar projections by the ligament 13, the-ends of which aresecured to the tensioning screws 14 having nuts 14 and being supportedby the plates 415 attached to the castings 3. Secured to and extendingdownwardly from the armature is the rod 16 which carries the stylus 17.If the device is to be used for cutting a master record or a record fromwhich others are to be made the stylus will have a suitable cuttingpoint while if the device is to be used as a pick-up in the reproductionof the recorded sound the stylus will have a point adapted to follow inthe record groove. Where the rod 16 passes through the bottom'plate 6 ofthe casing, I have .shown in Figs. 1 and 2 the sylphon diaphram 18secured at opposite ends to the rod and the plate. The diaphram 18 isvery light and flexible so as to offer a minimum resistance to themovements of the rod 16 yet effectively to retain the damping liquid. InFig. 3 I have illustrated a modified form of diaphram comprising therubber cap 20 secured as before to the rod 16 and the bottom plate 6.For fllingjand emptying the casing with damping liquid I have shown twoscrew plugs 21 in the top plate 5. A. certain amount of damping of themoving system is thus provided by the damping liquid which surrounds thearmature, the supporting ligament and portions of the rod 16 anddiaphram 18. To provide forgreater damping I have mounted the vane 23 onthe upper end of the armature in such a way that movements of thearmature cause a displacement of the damping liquid in the upper portionof the casing. For still further increasing and adjustably varying thedamping of the 9 each have two inwardly ex- V moving system I haveprovided a hollow downwardly opening member 24 which, guided by thecastings 3, is vertically movable to enclose more or less of the vane,it being understood that when the member is Iin its lowermost positionthe liquid offers the greatestfrictional resistance to movements of thevane and hence the maximum damping.

Member 24 is shown supported on the screw stud 25 extending through thetop plate 5 and through the strap 26 between which and the top plate isthe nut 27. By rotating the nut, the position of the member 24: may bevaried from without .the casing. It will be noted that the lower edgesof member 24 are rounded off to conform to the curved edges of thearmature and the polar projections when the member is in its extremelowermost position.

I have chosen the particular embodiment described above as illustrativeof my invention and it will be apparent that various mod ifications m'aybe made without. departing from the spirit and scope of my inventionwhich modifications I aim to cover' by the appended claims.

What I claim as new and desire to secure by Letters Patent of the UnitedStates, is z- 1. A phonograph device of the character describedcomprising a magnet, an armature mounted to vibrate adjacent thereto, astylus, a connection between the stylus and the armature, and a casingcontaining a` damping liquid enclosing the armature, said casing havinga flexible wall portion through which said connection extends. f

2. A phonograph device of the character a described comprising a magnet,an armature mounted for pivotal movement adjacent thereto, a stylusconnected with the armature, a casing containing a damping liquidenclosing the armature and a damping vane carried by the armature insaid liquid.

3. A phonograph device comprising a magnet, an armature pivotallymounted adto be moved from without the casing to cover said vane invarying amounts.

6. A phonograph device comprising a permanent magnet, a windingassociated with the poles thereof, an armature pivotally mountedadjacent said poles, a vane carried by the armature, a stylus, aconnection between the armature and the stylus, a casing forming achamber enclosing the armature and the vane, an adjustable hollow memberadapted to be moved to enclose varying amounts of the vane and meansexterior of' the casing for moving the member.

7.` A speech current apparatus including means for producing a magneticfield, a casing provided with a flexible wall portion, a damping fiuidin said casing, an armature immersed in said fluid and arranged to movein said field, and a movable member connected to said armature throughsaid fiexi-ble wall portion.

8. A speech current apparatus including means for producing a magneticfield, a casing, a fluid enclosed in said casing, an armature immersedin said fluid and arranged to move in said field, and a member arrangedto extend through said casing for moving said armature.

In witness whereof, I have hereunto set my hand this 9th day of March,1927.

LEWIS T. ROBINSON.

jacent thereto, a stylus connected therewith, A

a casing containing a damping liquid enclosing the armature, a vanecarried by the armature in the liquid, and means for varying the dampingeffect of the liquid on the vane.

4. A phonograph device comprising a magnet, an armature pivotallym'ounted adjacent thereto, a stylus connected therewith, a casingcontaining a damping liquid enclosing the armature, a vane carried bythe armature in the liquid, and a member associated with the vane foradjusting the damping effect of the liquid on the vane.

5. A phonograph device comprising a magnet, an armature pivotallymounted adjacent thereto, a stylus connected therewith, a casingcontaining a damping liquid enclosing the armature, a vane carried bythe armaturev in the liquid, and a hollow member arranged

